1. Sec61/SecY Protein review Sec61 protein is important for the movement of proteins across the cell membrane? A signal sequence guides the protein to the Sec61 protein? A plug model was put into play by this paper?

3. Lipid Membrane

4. More characteristics Driving Force of formation of lipid bilayer are Hydrophobic Interactions

5. Kinds of lipids in membrane Phospholipids Glycolipids cholesterol

6. Phospholipids PE- phosphatidyl ethanolamine PC- phosphatidyl choline SM- sphingomyleine PS- phosphatidyl serine Can serve as different markers for cell

7. Kyte Dolittle

8. K+ Channel Selective filter for moving potassium out of the cell Has four identical transmembrane subunits Each subunit has 2 transmembrane  helices and a third shorter helix called the pore helix These subunits form a central pore

9. K+ channel

10. Channel tilts outwards Has a loop that forms in channel and is going to make the selectivity filter, which will only allow K+ out Filter formed by carbonyl oxygens of the peptide backbone

11. K+ is 1.95 A NA+ is 0.95 A In the cell potassium will be hydrated with water and so will sodium Bonding between these elements and water will be a specific length Water needs to be shed in order for K+ to go through

12. Carbonyl oxygen will act as the surrogate water The dehydration of the ion takes energy but it is immediately made up by interactions with carbonyl oxygen Na is too small for this mechanism and therefore is not transported out

13. Porin Made by up and down  barrel Either 16 are 18 beta strands make up the porin Porin channel has a loop region in the middle of it which will act as a selective filter. 8 A in diameter Only certain small molecules will be able to transverse the membrane

15. Porin is made up of three channels as described

17. Bacteriarhodopsin 7 transmembrane alpha helices This protein is used for transforming light to chemical energy Proton pump

18. Retinol Bound in the pocket of the protein Undergoes isomerization when light hits it from trans to cis Bound covalently to lysine 216

19. The mechanism

22. Light at a certain wavelength cause change from trans to cis of retinal Then Asp transfers proton to schiff base This proton is then transferred to Asp 85 and then out to the extracellular space

23. Result Form an electrochemical gradient which is important for bacteria survival Use for generation of energy

24. Photosynthetic Reaction Center L, H, M and cytochrome subunits L and M subunits each have 5 hydrophobic transmembrane  helices H subunit has one transmembrane  helice

26. What is taking place Transfer of light to generate energy Players in the reaction must be arranged in a way that ensures the forward movement of the reaction Photons absorbed by chlorophylls